Why is the bible's teaching on sex good for society?

The Bible’s teaching is that sex is meant to take place in a sexually exclusive marital relationship between one man and one woman. In this context sex has three equally important functions. First, it consummates the union between a husband and wife. It is the physical means through which the two become ‘one flesh’ (Genesis 2:24). Secondly, it is a means through which, by the giving and receiving of physical pleasure, the love between a married couple is expressed and deepened (seen most fully in the Bible throughout Song of Songs). Thirdly, it is the normal and natural means by which a married couple can fulfil the God given mandate to ‘be fruitful and multiply’ (Genesis 1:28). Just as the God given purpose of food is to satisfy our hunger and the purpose of drink is to satisfy our thirst, so the God given purpose of sex is to fulfil these three ends within marriage.

In debating with Jewish leaders about sex and marriage, Jesus pointed back behind the law specifically given to Israel to God’s purposes in the creation of humanity (Matthew 19:3–12). Christians therefore believe that the Bible’s teaching on sex and marriage shows us one way we flourish as human beings made in God’s image. This means that it is not simply a set of rules for Christians but a pattern of life which non-Christians can recognise and experience as good. When people live according to biblical teaching it brings glory to God and helps us, as individuals and a society, to fulfil one of the purposes of our existence. In contrast, not abiding by this teaching harms members of society spiritually and potentially eternally. To put it another way, sinful sex (like all other forms of sin) poisons the soul. That is why Jesus warns against sexual sin in such drastic terms in Matthew 5:27–30.

In providing supporting evidence for this belief, care needs to be taken in appealing to anecdotal and survey evidence from specific social contexts, as conflicting accounts can be given. Furthermore, due to sin and what Jesus called our “hardness of heart”, as in Old Testament Israel, it will not always be appropriate for human laws to reflect the creation patterns of God’s best. Nevertheless, many people, both inside and outside the Church, can testify to the benefits of following the Bible’s teaching on sex and marriage and to how disregarding biblical teaching has had negative consequences for them, their families and others. There is now a wealth of research into the impact of developments in western society which have increasingly departed from biblical teaching in this area. For example, one important recent survey of this research reached the following conclusion:

"Over four decades of social science research across western nations confirms one clear and unambiguous conclusion: A healthy marriage is the best source of physical and mental health, emotional stability and prosperity for adults and children. It is also the best bet for attaining happiness and fulfillment …The healthy pair-bond of a man and a woman is the greatest hope of humanity, not just because it is a historically ubiquitous institution, but also because its critical role is supported by mounting social science research."

Maybe ‘I do’: Modern marriage and the pursuit of happinessKevin Andrews (2012)